In general, one can distinguish two types of video streaming services that are different in nature: broadcast services (the same content is streamed to several users watching simultaneously) and on-demand services (individualized content for one specific user). Examples of broadcast services are broadcast TV and multicast TV. Examples of on-demand services are time-shifted TV and video-on-demand. The way some of these services are currently implemented will be described in the following paragraphs.
In current packet based access/edge networks, live broadcast TV services or multicast TV services make use of a multicast architecture to deliver the TV channels to the end-users. The end-user typically uses a standardized multicast control protocol as request protocol to indicate which TV channel he/she wants to receive. An example of such a multicast control protocol is the Internet Group Management Protocol (IGMP) defined in Annex 1 of rfc 1112. The rfc 1112 from author S. Deering, entitled “Host Extensions for IP Multicasting” and published in August 1989, is retrievable from the IETF website on the Internet via the URL: http://www.ieff.org/rfc/rfc1112.txt?number=1112
To receive a broadcast or multicast TV channel, the host—e.g. the end user's set-top box featuring an IGMP client—exchanges IGMP messages with the network in order to join the multicast group for that TV channel. In the network, the access and/or edge nodes play an active role in packet based broadcast or multicast TV services by acting as an IGMP proxy. Alcatel's 7302 Intelligent Service Access Manager (ISAM) for instance has IGMP proxy functionality integrated on the linecards. A product brochure for release 2.1 of Alcatel's 7302 ISAM is available through the Internet via the following URL: http://www.alcatel.com/products/productsummary.jhtml?relativePath=/com/en/app/xml/opgproduct/alcatel7302intelligentservicesaccessmanagertcm228121931635.jhtml
Paradyne's 4200 series of IP DSLAMs have an IGMP snooping and IGMP proxy function on the network interface card. A data sheet for Paradyne's 4200 IP DSLAM products is accessible via the URL: http://www.paradyne.com/products/4200IP/
The IGMP proxy functionality enables the access/edge node to intercept and interpret the IGMP requests received from end-users. This is often called state-based IGMP processing in literature. If the access/edge node already receives the requested TV channel, e.g. because another subscriber connected to this access/edge node is already watching the TV channel, then the TV channel will be forwarded to the new end-user requesting the TV channel. If the access/edge node does not yet receive the requested TV channel, then the IGMP join message received from the end-user will be forwarded to pull the requested TV channel from a multicast supporting node deeper in the network. Similarly, an IGMP leave message sent by an end-user who wants to stop watching a broadcasted or multicasted TV channel, is intercepted by the IGMP proxy in the access/edge node and only forwarded if needed.
Time-shifted TV is a service that enables the end-user to watch a broadcasted TV programme with a time shift, i.e. the end-user can start watching the TV programme from the beginning although the broadcasting of that TV programme has already started or is already finished. Dedicated home equipment, for instance a home Personal Video Recorder or home PVR device like Sony's High Definition Digital Video Recorder DHG-HDD500 enable time-shifted TV through a built-in memory (a hard disk or RAM) that can be programmed to record broadcasted TV programmes. The home PVR device enables recording a TV show and watching it at a later time, watching the show while it is being recorded, and watching a previously recorded show while simultaneously recording another TV show. Certain home PVR devices further have advanced features like pausing or rewinding while watching a broadcasted TV programme. To pause a broadcasted TV programme while watching it, the home PVR starts recording the broadcasted programme that is being watched and continues playing the programme on instruction of the viewer while it keeps recording the ongoing broadcast. There are however some limitations to time-shifted TV through home PVR devices because of the limited storage capacity and also the access link to the end-user's home (for instance an ADSL connection) has capacity or bandwidth restrictions. xDSL technologies for instance can serve in the order of 1-5 TV channels simultaneously. As a consequence, a home PVR device will always need programming in advance and the device will never be capable to record more than a few programmes or TV channels simultaneously.
A time-shifted TV service can also be offered through PVR functionality in the network. An example thereof is the distributed PVR solution described in Alcatel's earlier filed European Patent Application No. 05291959.4 filed on 21 Sep. 2005 with the European Patent Office. In principle, such network PVR solution enables the end-user to watch at any time any programme broadcasted on any channel. The end-user experience is similar to a video-on-demand service, but the content is live broadcasted or multicasted TV with an arbitrary time shift relative to the original broadcast time. For time-shifted TV service, the end-user typically uses an on-demand request protocol like for instance the Real Time Streaming Protocol or RTSP defined in rfc 2326, which is accessible via Internet URL: http://www.ieff.org/rfc/rfc2326.txt?number=2326
Video-on-demand is a streaming video service whereby the end-user can watch at any time content which is stored in a video server. The end-user again typically uses an on-demand request protocol like RTSP or SDP (Session Initiation Protocol). Assuming that RTSP is used as the on-demand request protocol for an on-demand service like video-on-demand (VoD), near video-on-demand (NVoD) or pay-per-view video, the streaming requests from the end-user are terminated on an RTSP proxy located near the video server, like for instance the SeaChange Session Resource Manager described in SeaChange's white paper “Video over IP” retrievable via the URL: http://www.schange.com/Downloads/IP_Streaming/VODOVERIP_WhitePaper.pdf
For an on-demand service like time-shifted TV service implemented through distributed PVRs in access/edge nodes, the RTSP proxy intercepting the streaming requests from end-users might be integrated in the access/edge nodes as is suggested in Alcatel's European Patent Application EP 05291959.4 filed on 21 Sep. 2005 with the European Patent Office. Therein, the User Request Termination 413 in the onboard processor drawn in FIG. 4 may represent an RTSP proxy.
Summarizing the foregoing, according to the current state of the art, broadcast/multicast TV services on the one hand and on-demand video services like VoD, NVoD or time-shifted TV on the other hand are offered on different platforms with different request protocols, different network elements and proxies, different management and control functions involved. This results in over-complication of both the end-user equipment (e.g. the STB) and the proxy element logistics in the network nodes. An example prior art system is for instance drawn in FIG. 1. The Digital Subscriber Line Access Multiplexer (DSLAM) 100 depicted there is an access node that has separate platforms for broadcast services and on-demand services. For broadcast services, the IGMP proxy 101 intercepts IGMP requests received at port 111 at subscriber side, interprets these IGMP requests and forwards them to the next network node in the broadcast or multicast network via port 112 if needed. For on-demand services, RTSP proxy 102 intercepts RTSP requests received at port 113 at subscriber side, interprets these RTSP messages and forwards them to the next network node in service-on-demand network via port 114 if needed. The RTSP messages intercepted by RTSP proxy 102 are used to control a video programme cache memory 103 that is used for time-shifted TV service.
Separate platforms for different streaming video services further result in enhanced CAPEX and OPEX for the network operator because the bandwidth and storage resources cannot be deployed optimally.
In addition, having separate control and delivery platforms for broadcast TV services and on-demand services prevents the network nodes for instance from taking advantage of information that could be derived from monitoring the broadcast TV behaviour for updating the record profiles/algorithms used by the network PVRs for the time-shifted TV service. Vice-versa, information that could be derived from on-demand video services indicative for the capabilities of for instance the STB, is not taken advantage of to enable for instance a user-centric broadcast TV service wherein the delivered broadcast TV stream is adapted to the end-user's terminal capabilities (for instance through transcoding, authorization, access control, etc.).
An objective of the invention is to provide access/edge nodes that support multiple streaming video services without the above mentioned shortcomings of the state of the art solutions.